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Wastewater Characteristics Blackwater will originate from toilets and graywater from showers, laundry, dishwashing,hand washing, etc. Additional wastewater constituents may consist of other liquids to the system. The per capita intake of nitrogen per day provides the basis for calculating the nitrogen balance of inflows and outflows. The USEPA Design Manual states Total Nitrogen concentrations between 6 to 17 grams of nitrogen per capita per day. Dr. Stewart Oakley of Chico State University, one of the world's leading researchers in wastewater management, uses 15 grams of N per person per day in his calculations. This figure will be used in the nitrate loading calculations below. B. CALCULATED NITRATE-NITROGEN LOADING NLS§3.3,3.4,3.5,3.6. The calculated nitrate-nitrogen impact to the soil and potentially to the groundwater is difficult to determine due to the large number of variables involved and variables unknown at this time. These include: 1.) Impact from upgradient agricultural sources, 2.) Variability in wastewater flows,nitrogen concentrations and dilution effects from stormwater recharge, 3.) Changes in groundwater directional flow and elevation, 4.) Denitrification potential within the loam soil fractions, and within confined and/or unconfined aquifers. The Hantzsche/Finnemore Formula is used below to predict the average resultant concentration of nitrate-nitrogen in effluent recharge water. As calculated below,the property has been assessed on a total areal loading basis correlated with the total projected yearly wastewater flow volumes calculated above. These two factors primarily estimate the average resultant concentration of nitrate-nitrogen in the recharge water and is exceeded of the concentration is more than 10 ppm nitrate-nitrogen(45 ppm as nitrate). Calculated Nitrate-Nitrogen Loading: INw(1 -d)+R Nb Nr= (I+R) Where: Nr = Resultant average concentration of nitrate-nitrogen in recharge water-(ppm NO3-N) I = Volume rate of wastewater entering the soil averaged over the gross developed area in inches per yr Nw = Total nitrogen concentration in raw wastewater in mg N/L d = Fraction(%)of nitrate loss due to denitrification in the soil profile. R = Average recharge rate of rainfall-inches per yr Nb = Background nitrate-nitrogen concentration of rainfall recharge,exclusive of wastewater influences (ppm NO3-N). Page -7- Chesney Consulting,